The Nervous System (brain) & The Endocrine System (hormones)

 The Nervous System - your bodies communication system!


The Nervous system has three major functions:
1. Sensory – monitors and responds to internal & external stimuli to maintain homeostasis.
2. Motor – control movement
3. Regulation - reg
ulates bodily functions

The Brain Videos...Watche them all!

The Organs of the Nervous system1. brain
2. spinal cord
3. nerves
4. sensory organs - the eyes, ears, nose, tongue and sensory receptors in skin,
     joints, muscles and other parts of the body.
Video on Neurons

Bill Nye on the Brain

3 types of Neurons

Motor neurons communicate to move muscles

Sensory neurons communicate with your senses

Interneurons are nerve cells found entirely within the central nervous system that acts as a link between sensory neurons and motor neurons.
How does the nervous system interact with other body systems? Click here!

The human nervous system consists of billions of nerve cells (or neurons) plus supporting (neuroglial) cells. Neurons are able to respond to stimuli (such as touch, sound, light, and so on), conduct impulses, and communicate with each other (and with other types of cells like muscle cells).
Parts of a Neuron
Soma - the cell body
The Nucleus of a neuron is located in the cell body.
Dendrites extend out from the cell body and receive messages from the axon terminal during a synapse.
Axons extend out from the cell body and send messages during a synapse.
Myelin sheath surrounds the axon and helps move impulses faster.

Impulses typically travel along neurons at a speed of anywhere from 1 to 120 meters per second!

The axon of one neuron doesn't touch the dendrites of the next. Nerve signals have to move across a tiny gap, the Synaptic Gap. To get across the gap they have to change from electrical signals into chemical signals then back into electrical signals.

The Nervous System is divided into 2 parts.
Click here for the Powerpoint
The central nervous system (CNS)        spinal cord
Its main job is to get the information from the body and send out instructions.
The peripheral nervous system (PNS)
        nerve tissue outside the brain
        sensory organs
This system sends the messages from the brain to the rest of the body.
The peripheral nervous system is divided into two major parts:
            somatic nervous system - controls voluntary functions, movement, controls the skeletal     
autonomic nervous system - controls involuntary functions, controls cardiac and smooth
             muscles, and glands.
The autonomic nervous system is divided into two major parts:
                                      the sympathetic system- fight or flight, stimulatory stress responses.
                                      the parasympathetic system -  rest and digest, salavation, digestion, dilation

Glands...what glands? The Endocrine System!
The endocrine system is the system of glands, each of which secretes different types of hormones directly into the bloodstream to regulate the body.

Illustration of the Endocrine System


What is a hormone? It is a chemical that has a high level of specificity, which means that it will only react with a specific receptor site in your body. The lock and key analogy is often used to explain this specificity, and it is a great way to think about how hormones work. Hormones convey important information to the body, including such instructions as cell division and growth, appetite suppression, acid secretion, calcium absorption, and red and white blood cell production. Hormones are secreted by endocrine glands. There are eight major endocrine glands. Those glands, along with their main functions, are listed below:

Pituitary gland - regulates other endocrine glands; secretes growth hormone.
           Thyroid - regulates metabolic rate.
           Thymus - assists in development of immune system.
           Adrenal gland - regulates fluid and sodium balance; emergency warning system under stress.
           Ovary - controls development of secondary sex characteristics and functioning of sex organs.
           Testis - controls development of secondary sex characteristics and functioning of sex organs.
           Pancreatic islets - helps regulate blood sugar.
           Pineal gland - believed to regulate biorhythms and moods and stimulate the onset of puberty.
Fight or Flight ResponsesWhen our senses perceive an environmental stress such as danger or a threat, cells in the nervous and endocrine systems work closely together to prepare the body for action. Often referred to as the fight or flight or stress response, this remarkable example of cell communication elicits instantaneous and simultaneous responses throughout the body.
 How does the body do it? The hypothalamus...

Your Senses can fool you...Check out these cool illusions Auditory Illusions Optical Illusions 1 Optical Illusions 2 Optical Illusions 3

Optical Illusions 4

Can you say the color name not read the word?

Your Brain processes words and reading first, thats what makes this tsak so difficult...
That's all for now....
Mrs. Sandoval



The Excretory Story

Excretory System (a. k. a. Urinary System)
Have you ever wondered why your body has to urinate? Where does that fluid come from? Why is it yellow? You'll learn the answers to these and more questions as you read our information about the excretory system. Video        Song
Parts of the Excretory System
 the kidneys: they contain filters that take the waste out of the blood
 the nephrons: remove the waste materials from blood and make urine
 the ureters: tubes that carry the urine to the bladder
 the bladder: a 'bag' that collects the urine
 the urethra: a tube that carries the urine out of the body

What does the excretory/urinary system do?

The kidneys, the bladder, and their tubes all work together to form the urinary system. Waste that's left over from breaking down food and your body's other activities naturally builds up in your blood. Your blood passes through your kidneys and when this happens, your kidneys act like a filter to clean the waste from your blood. Then they mix the waste with a little water to create urine. The urine goes to your bladder, which you empty when you urinate (pee). Kidneys and Nephrons

One of the main jobs of the kidneys is to filter the waste out of the blood. First, blood is carried to the kidneys by the renal artery. As the blood passes through the kidneys, it deposits used and unwanted water, minerals, and a nitrogen-rich molecule called urea. More than 1 million tiny filters inside the kidneys remove this waste. These filters, called nephrons, are so small you can see them only with a high-powered microscope.

Kidneys normally come in pairs. If you've ever seen a kidney bean, then you have a pretty good idea what the kidneys look like. Each kidney is about 5 inches long and about 3 inches wide.

 Ureter, Bladder and Urethra The waste that is collected combines with water (which is also filtered out of the kidneys) to make urine. As each kidney makes urine, the urine slides down a long tube called the ureter and collects in the bladder, a storage 'bag' that holds the urine. When the bladder is about halfway full, your body tells you to go to the bathroom. When you urinate, the urine goes from the bladder down another tube called the urethra and out of your body.

If the urinary system is healthy, the bladder can hold up to 16 ounces (2 cups) of urine comfortably for 2 to 5 hours.

What happens to the skeletal system when the kidneys fail? Click Here

More about the kidneys...
Although the kidneys are small organs by weight, they receive a huge amount -- 20 percent -- of the blood pumped by the heart. The large blood supply to your kidneys enables them to do the following tasks:
  • Regulate the composition of your blood: Keep the concentrations of various ions and other important substances constant; Keep the volume of water in your body constant; Remove wastes from your body (urea, ammonia, drugs, toxic substances); Keep the acid/base concentration of your blood constant
  • Help regulate your blood pressure
  • Stimulate the making of red blood cells
  • Maintain your body's calcium levels
More Information

Fun Facts
      1. Our blood passes through our kidney's 300 times a day.
2. our nephrons can clean our blood within 45 minutes.

3. Everyday our nephrons send 6 cups of urine to our bladder
          4. The average person pees about 3000 times a year.
          5. The average person poops about 305 pounds a year.
          6. The liver is rubbery to touch.

Why is urine yellow?
Some European alchemists in the middle ages apparently thought one possible reason was that there was gold in urine. This led to fruitless, and possibly quite disgusting, efforts to extract that gold.

The yellow color in urine is due to chemicals called urobilins. These are the breakdown products of the bile pigment bilirubin. Bilirubin is itself a breakdown product of the heme part of hemoglobin from worn-out red blood cells. In the bloodstream the Bilirubin is extracted by the kidneys where, converted to urobilins, it gives urine that familiar yellow tint.

Why does urine change colors?
You might notice that sometimes your urine is darker in color than other times. Remember, urine is made up of water plus the waste that is filtered out of the blood. If you don't take in a lot of fluids or if you're exercising and sweating a lot, your urine has less water in it and it appears darker. If you're drinking lots of fluids, the extra fluid comes out in your urine, and it will be lighter.

Beets turn your urine pink.

The Digestive System

The Digestive System breaks down the food we eat into chemicals that the body can use. 

Digestive system is a group of organs that work together to break down the chemical components of food into small nutrients that can be absorbed by cells to create energy for the body.

Some of the organs involved in digestion are the mouth, esophagus, stomach, small and large intestines, gallbladder, pancreas and liver.

Food broken down by our digestive system is moved to every part of our body by our circulatory system.
Digestion involves...
  1. The mixing of food
  2. Its movement through the digestive tract
  3. The chemical breakdown of the large molecules of food into smaller molecules.
Watch this video about digestion    or this one or Learn more here
    Mouth - We chew our food with our mouth and our tongue is a muscle that works with saliva to form a ball that can be swallowed.
    The esophagus is simply a transportation tube from the mouth to the stomach.
    The stomach uses chemicals to try to make the food particles tinier. These chemicals are called gastric juices and they include hydrochloric acid and enzymes (chemicals that break down food). The food is moved around in the stomach and mixed with the chemicals for 3-4 hours. When the stomach is finished with it, the food is a creamlike liquid call chyme.
    The liver makes a chemical called bile, and it is stored in the gall bladder.
    When the gall bladder mixes bile with our food, it does an important job:
    breaking down the fat (from milk, butter, cheeses) into tiny droplets. This
    fat will supply us with much energy later.
    The pancreas also adds a digestive chemical as the food
    leaves the stomach. This digestive juice works on breaking down the carbohydrates
    (from breads, potatoes, pasta, etc.) and the proteins (from
    meats, eggs, peanut butter, etc.)
    The small intestine  is where the real digestion takes place. As the food passes through, it is mixed with the new chemicals, and is finally digested enough to be put to use by the body. Along the walls of the intestine are thousands of tiny fingers
    called villi. Blood vessels (capillaries) in the villi can absorb the tiny food molecules and send them off to the rest of our body through the blood.
    Large Intestine whatever the body cannot put to use is sent to the large intestine. Many plants, for example, contain cellulose, which cannot be digested.The big job of the large intestine is to remove water.

    The small intestine is the real hero of the digestive system.
    The small intestine is a tube that is about 18 feet long!

Interactive Organs Here!

Small Intestine  X-Ray Image from Thibodeau
X-ray image of a large intestine

Watch a cartoon about the Digestive System

Learn more about the Digestive Organs here

Interesting Stuff....
1.. For every 2 weeks, the human stomach produces a new layer of mucous   
lining, otherwise the stomach will digest itself.

2. The human liver performs 500 different functions.

3. Liver is the largest and heaviest internal organ of the body and weighs about 1.6 kilos.

4. The Liver is the only organ of the body, which has the capacity to regenerate itself completely even after being removed almost completely.

5. Liver cells take several years to replace themselves.

6. A healthy liver processes 720 liters of blood per day.

7. The human stomach contains about 35 million small digestive glands.

8. The human stomach produces about 2.5 liters of gastric juice everyday.

9. In an average person, it takes 8 seconds for food to travel down the food pipe, 3-5 hours in small intestine and 3-4 days in the large intestine.

10. The human body takes 6 hours to digest a high fat meal and takes 2 hours for a carbohydrate meal.